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Innate Immunity Cellular Responses (view source)
Revision as of 15:57, 13 August 2010
, 15:57, 13 August 2010Created page with "thumb|right|125px|<p>'''Macrophage'''</p><sup>© Nottingham Uni</sup> * If pathogens breach the barriers formed by the skin and mucus membra..."
[[Image:LH Macrophage Histology.jpg|thumb|right|125px|<p>'''Macrophage'''</p><sup>© Nottingham Uni</sup>]]
* If pathogens breach the barriers formed by the skin and mucus membranes, they must be detected and destroyed by cellular and humoral means
* The cells involved with innate protection are:
** Blood granulocytes, or Polymorphonuclear Cells
*** Notable for their multi-lobed nuclei
*** '''Neutrophils''': phagocytose bacteria
*** '''Eosinophils''': kill parasites by the release of granules
*** '''Basophils/ mast cells''': kill parasites by the release of granules
** Blood '''[[[[Monocytes|monocytes]]]]''': phagocytose bacteria
** Tissue mast cells and '''macrophages''': phagocytose bacteria
*Effectively, innate cellular response seeks to hold off the infection until the [[Adaptive Immune System - WikiBlood|adaptive]] response can back it up with a more specific attack
===[[Macrophages|Macrophages]]===
[[Image:Monocytes.jpg|thumb|right|150px|Monocytes - J. Bredl, RVC 2008]]
*The role of macrophages in Innate Immunity is to act as primary '''phagocytes'''
* Macrophages are present within tissues and take the form of distinct, tissue-specific populations:
** Alveolar macrophages
** Tissue histiocytes
** Glomerular macrophages
** Hepatic Küpffer cells
** CNS microglia
** Sinus-lining macrophages of the lymph nodes and spleen
* [[Monocytes|'''Monocytes''']] (immature macrophages) are circulating phagocytes
** Circulate for 6-8 hours
** Can function as phagocytes within the blood and as newly migrated cells in tissues
** Chiefly function to replace the various tissue macrophage populations
===[[Neutrophils|Neutrophils]]===
[[Image:Neutrophil 2.jpg|thumb|right|150px|Neutrophils - J. Bredl, RVC 2008]]
* Neutrophils are the principal, highly active '''phagocytes''' in the blood
** Comprise 30-70% of white blood cells depending on species
** Kill and digest microbes in a similar way as macrophages
* Neutrophils can also cause extracellular bacterial killing by disrupting bacterial membranes
** Secrete small antibacterial peptides
*** E.g. defensins and bactenecins
* Neutrophils produce vasoactive peptides
** E.g. histamine and bradykinin
** Cause a great increase in extravasation of blood granulocytes and [[Monocytes|monocytes]] and plasma proteins at the site of infection
* Neutrophils are the archetypal cell associated with [[Inflammation - WikiBlood|acute inflammation]]
** Are attracted to sites of inflammation by:
*** Complement activation
*** Cytokine production
*** Changes to vascular endothelium
** Neutrophil activation in an inflammatory lesion results in the release of '''prostaglandins'''
*** Responsible for vasoactive changes and for pain
* The accumulation of dead and dying [[Neutrophils|neutrophils]] at the site of infection is called '''pus'''
** Their removal from the site after the removal of infection is an important step in the resolution of the lesion
===[[Eosinophils|Eosinophils]]===
[[Image:Eosinophil.jpg|thumb|right|150px|Eosinophil - J. Bredl, RVC 2008]]
* Eosinophils are less common than [[Neutrophils|neutrophils]], and they are not phagocytic
** Make up <5% of the leukocytes in normal blood
* Eosinophil numbers are increased:
** Slightly during the resolution phase of inflammation
** Many-fold in parasite-infected animals
*** The presence of a large proportion of eosinophils in a blood smear is highly indicative of parasitaemia
* Mainly function by targeting the surface of parasites by means of specific antibody or complement
** Release a large range of toxic molecules that break down the parasite integument
* Prominent in [[:Category:Allergic Diseases|allergic]] (anaphylactic) reactions
===[[Basophils|Basophils]] / [[Mast Cells|Mast Cells]]===
[[Image:Basophil and Lymphocyte.jpg|thumb|right|150px|Basophil - J. Bredl, RVC 2008]]
* Basophils/mast cells are principally localised at epithelial surfaces
** Very small numbers are present in blood
*** Less than 0.5% circulating leukocytes
* They have two principal functions:
*# Induction of [[Inflammation - WikiBlood|acute inflammation]]
*#* Trauma and/ or bacterial infection causes the production of '''cytokines''' by the mast cells that induce a classical acute inflammatory response
*# Response to parasite infection
*#* Specific [[Immunoglobulins|IgE]] binds cells
*#* Subsequent contact with antigen causes the mast cells to degranulate
*#* Release enzymes and vasoactive substances that can result in a high level of mucus secretion and smooth muscle contraction
* Also produce factors that influence local host cell physiology
** Various mediators increase the ratio of phagocyte to microbe
[[Category:Innate Immune System]]
* If pathogens breach the barriers formed by the skin and mucus membranes, they must be detected and destroyed by cellular and humoral means
* The cells involved with innate protection are:
** Blood granulocytes, or Polymorphonuclear Cells
*** Notable for their multi-lobed nuclei
*** '''Neutrophils''': phagocytose bacteria
*** '''Eosinophils''': kill parasites by the release of granules
*** '''Basophils/ mast cells''': kill parasites by the release of granules
** Blood '''[[[[Monocytes|monocytes]]]]''': phagocytose bacteria
** Tissue mast cells and '''macrophages''': phagocytose bacteria
*Effectively, innate cellular response seeks to hold off the infection until the [[Adaptive Immune System - WikiBlood|adaptive]] response can back it up with a more specific attack
===[[Macrophages|Macrophages]]===
[[Image:Monocytes.jpg|thumb|right|150px|Monocytes - J. Bredl, RVC 2008]]
*The role of macrophages in Innate Immunity is to act as primary '''phagocytes'''
* Macrophages are present within tissues and take the form of distinct, tissue-specific populations:
** Alveolar macrophages
** Tissue histiocytes
** Glomerular macrophages
** Hepatic Küpffer cells
** CNS microglia
** Sinus-lining macrophages of the lymph nodes and spleen
* [[Monocytes|'''Monocytes''']] (immature macrophages) are circulating phagocytes
** Circulate for 6-8 hours
** Can function as phagocytes within the blood and as newly migrated cells in tissues
** Chiefly function to replace the various tissue macrophage populations
===[[Neutrophils|Neutrophils]]===
[[Image:Neutrophil 2.jpg|thumb|right|150px|Neutrophils - J. Bredl, RVC 2008]]
* Neutrophils are the principal, highly active '''phagocytes''' in the blood
** Comprise 30-70% of white blood cells depending on species
** Kill and digest microbes in a similar way as macrophages
* Neutrophils can also cause extracellular bacterial killing by disrupting bacterial membranes
** Secrete small antibacterial peptides
*** E.g. defensins and bactenecins
* Neutrophils produce vasoactive peptides
** E.g. histamine and bradykinin
** Cause a great increase in extravasation of blood granulocytes and [[Monocytes|monocytes]] and plasma proteins at the site of infection
* Neutrophils are the archetypal cell associated with [[Inflammation - WikiBlood|acute inflammation]]
** Are attracted to sites of inflammation by:
*** Complement activation
*** Cytokine production
*** Changes to vascular endothelium
** Neutrophil activation in an inflammatory lesion results in the release of '''prostaglandins'''
*** Responsible for vasoactive changes and for pain
* The accumulation of dead and dying [[Neutrophils|neutrophils]] at the site of infection is called '''pus'''
** Their removal from the site after the removal of infection is an important step in the resolution of the lesion
===[[Eosinophils|Eosinophils]]===
[[Image:Eosinophil.jpg|thumb|right|150px|Eosinophil - J. Bredl, RVC 2008]]
* Eosinophils are less common than [[Neutrophils|neutrophils]], and they are not phagocytic
** Make up <5% of the leukocytes in normal blood
* Eosinophil numbers are increased:
** Slightly during the resolution phase of inflammation
** Many-fold in parasite-infected animals
*** The presence of a large proportion of eosinophils in a blood smear is highly indicative of parasitaemia
* Mainly function by targeting the surface of parasites by means of specific antibody or complement
** Release a large range of toxic molecules that break down the parasite integument
* Prominent in [[:Category:Allergic Diseases|allergic]] (anaphylactic) reactions
===[[Basophils|Basophils]] / [[Mast Cells|Mast Cells]]===
[[Image:Basophil and Lymphocyte.jpg|thumb|right|150px|Basophil - J. Bredl, RVC 2008]]
* Basophils/mast cells are principally localised at epithelial surfaces
** Very small numbers are present in blood
*** Less than 0.5% circulating leukocytes
* They have two principal functions:
*# Induction of [[Inflammation - WikiBlood|acute inflammation]]
*#* Trauma and/ or bacterial infection causes the production of '''cytokines''' by the mast cells that induce a classical acute inflammatory response
*# Response to parasite infection
*#* Specific [[Immunoglobulins|IgE]] binds cells
*#* Subsequent contact with antigen causes the mast cells to degranulate
*#* Release enzymes and vasoactive substances that can result in a high level of mucus secretion and smooth muscle contraction
* Also produce factors that influence local host cell physiology
** Various mediators increase the ratio of phagocyte to microbe
[[Category:Innate Immune System]]